1. (a) Field of the Invention
The present invention relates to a plasma reactor, and more particularly, to a plasma reactor for attaining an environmentally friendly process by decomposing and removing various hazardous materials in a front end part of a vacuum pump.
2. (b) Description of the Related Art
A process chamber for performing processes such as etching, deposition, cleaning, and so on is installed in a manufacturing line of a semiconductor, a display, a solar cell, and the like, and the process chamber is connected to a vacuum pump to evacuate process gases. Various hazardous materials are discharged from the process chamber, for example, greenhouse gases such as CF4, CHF3, C2F6, C4F8, etc., are discharged in the etching process, an undecomposed precursor is emitted in the deposition process, and greenhouse gases and particle by-products such as NF3, SF6, etc. are discharged in the cleaning process.
Restrictions on emissions of the greenhouse gases that cause global warming have been tightened, and the particle by-products deteriorate the vacuum pump while accumulated in the vacuum pump. Most of the precursor used in the deposition process is injected inside of the vacuum chamber in a liquid phase or is vaporized by a bubbler, etc., and the discharged precursor which is not used in the deposition process is the undecomposed precursor. The undecomposed precursor is accumulated inside of the vacuum pump or between the vacuum pump and a scrubber.
Since there is a high temperature difference inside of the vacuum pump when in the operating and non-operating states, the undecomposed precursor in a vapor state and a liquid state coexist. As a result, this may cause an explosion when being excessively expanded while expansion and shrinking are repeated. In addition, the undecomposed precursor accumulated between the vacuum pump and the scrubber is exposed when replacing the vacuum pump, the scrubber, or pipe, and some of this may cause a fire while violently reacting with air.
A plan for utilizing a plasma reactor has been researched in order to decompose or remove various hazardous materials discharged in a process chamber. However, in a case that the hazardous materials flow through the inside of the plasma reactor, problems have been reported that the precursor decomposed by plasma is deposited on a insulator surface of the plasma reactor, or the particle by-products decomposed by plasma and fluorine radicals decomposed from the greenhouse gases etch the insulator surface. A thickness increase of the insulator due to the deposition causes a decrease in decomposition rate of the hazardous materials, and the etching of the insulator causes insulation breakdown.
Also, in the decomposition process of the hazardous materials using plasma, oxygen radicals and hydrogen radicals are required to stabilize the greenhouse gases, and for this, a method of inputting water vapor (H2O) to a front part of the plasma reactor is conventionally used.
However, although the method of inputting the water vapor is good in terms of safety of the process, it has drawbacks that the decomposition rate of the greenhouse gases is low and the amounts of oxygen and hydrogen are unable to be individually controlled. In addition, there is a technical difficulty in finely controlling the input of water vapor, and there is a limit that the entire system becomes complex since additional equipment such as a bubbler are required.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.